A typographical error made while using thumbs only to text mesage. Similar to a typo, or typographical error.
Did you mean to write guck you? No, sorry, that was a thumbo.
מאת The Pigfarmer's Grandson 3 באוקטובר, 2009
Refers to a clumsy person with a distinct lack of coordination with his hands.
He's such a thumbo, he cant catch a pass to save his ass.
מאת upriverman 2 במרץ, 2004